Electric reagent launcher for reduction of nitrogen

ABSTRACT

A selective catalytic reduction system (SCR) or selective non-catalytic reduction (SNCR) system include a reagent charging apparatus configured to apply one or more electrical charges to a NOx reducing reagent. The electrical charges enhance mixing of the reagent with fluids carrying NOx and/or enhance reactivity of the reagent with NOx.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority benefit from U.S. ProvisionalPatent Application No. 61/683,177, entitled “CHARGE-INDUCED SELECTIVENON-CATALYTIC REDUCTION (SNCR) OF NITROGEN”, filed Aug. 14, 2012; which,to the extent not inconsistent with the disclosure herein, isincorporated by reference.

BACKGROUND

Oxides of nitrogen (NOx) are undesirable byproducts of combustion of afuel in air. Some fuels, such as coal and biomass provide additionalnitrogen and can be more problematic. Unfortunately, combustion ofinexpensive fuels such as coal, biomass, and waste may tend to producethe most NOx. Regulations and general concerns for air quality havecaused manufacturers and operators of combustion systems to seek ways todecrease emissions of NOx from combustion processes.

One approach to decrease the output of thermal NOx is to decreasepeak-combustion reaction temperature. Another approach to decrease theoutput of NOx is to convert NOx present in post-combustion gases intomolecular nitrogen, N₂. Since NOx is an oxidized form of nitrogen,conversion of NOx to N₂ is referred to as nitrogen reduction. Selectivenitrogen reduction processes including selective catalytic reduction(SCR) and selective non-catalytic reduction (SNCR) are used tochemically reduce oxides of nitrogen (NOx) to molecular nitrogen, N₂.

NOx typically includes NO and NO₂, but at high temperatures is usuallydominated by NO. In SNCR, a nitrogen compound such as ammonia (NH₃),urea (NH₂CONH₂), or another reagent is injected into hot (but not toohot) combustion fluids, such as in a firebox or boiler. If urea isinjected, it reacts to form ammonia according to reaction (1):

(1)

NH₂CONH₂+½O₂→2 NH₃+CO₂

The nitrogen reduction reaction may be expressed as:

(2)

4NO+4NH₃+O₂→4N₂+6H₂O

The mechanism for reaction (2) involves the formation of intermediate.NH₂ radicals that react with NO to form the reaction products N₂ andH₂O.

One complication with the chemistries described above relates totemperature. At temperatures above 1093° C., ammonia decomposes to formNO according to reaction (3):

(3)

4NH₃+5O₂→4NO+6H₂O

Other complications to operation of SCR/SNCR systems relate tonon-uniform NOx distribution in a combustion volume or flue gas anddelivery of an appropriate amount of reducing agent to the NOxdistribution. Since central regions of fireboxes and furnaces tend to behotter than regions near firebox and furnace walls, more NO tends to beformed near the center. Thus, uniform distribution of NH₃ across acombustion volume will not result in uniform reduction in NOx. Moreover,it can be difficult to distribute NH₃ to areas where it is needed.

Generally, existing SCR/SNCR systems suffer from ammonia slip (passageof unreacted ammonia out a flue) and lower than theoretical efficiency(equilibrium) with respect to removal of NOx.

What is needed is a technology that can improve performance and/orreduce costs of SCR and SNCR systems.

SUMMARY

According to an embodiment, a charge-induced selective catalyticreduction (SCR) or selective non-catalytic nitrogen oxide (NOx)reduction (SNCR) system is provided. The charge-induced SCR or SNCRsystem includes a reagent charging apparatus configured to applyelectrical charges to a reagent or a fluid carrying the reagent toproduce a charged reagent. The reagent can include molecules, anaerosol, droplets, or particles, for example. The SCR or SNCR systemincludes a reagent launcher operatively coupled to the reagent chargingapparatus. The reagent launcher is configured to launch the chargedreagent proximate to a combustion reaction or flue gas produced by thecombustion reaction. Opposite polarity charges carried by the combustionreaction or flue gas can attract the charged reagent toward a reactionzone. Alternatively, a counter-electrode carrying a voltage opposite inpolarity from the reagent charge can attract the charged reagent towardthe reaction zone.

According to an embodiment, a method for operating a nitrogen oxide(NOx) control system is provided. The method includes applying firstelectrical charges to an SCR or SNCR reagent and contacting the chargedreagent with a combustion reaction or a flue gas from a combustionreaction. The first electrical charges are selected to enhance mixing ofthe SCR or SCNR reagent with NOx-carrying fluids and/or to enhancereactivity of the reagent with NOx. For example, the first electricalcharges can be opposite in polarity to charges carried by the combustionreaction or flue gas. Additionally or alternatively, the firstelectrical charges can be opposite in polarity to a voltage carried by acounter-electrode positioned to draw the reagent across the combustionreaction or flue gas. Additionally or alternatively, the firstelectrical charges can be the same polarity as a voltage carried by alaunching electrode positioned to repel the reagent across thecombustion reaction or flue gas. The reagent reduces the NOx tomolecular nitrogen (N₂).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram depicting a charge-induced selectivenon-catalytic reduction (SNCR) system for reducing nitrogen oxides (NOx)to molecular nitrogen (N₂), according to an embodiment.

FIG. 2 is a block diagram depicting a charge-induced selective catalyticreduction (SCR) system for reducing nitrogen oxides (NOx) to molecularnitrogen (N₂), according to an embodiment.

FIG. 3 is a block diagram of an embodiment of a reagent launcherconfigured to vaporize and charge the reagent.

FIG. 4 is a block diagram of an embodiment of a reagent launcherconfigured to entrain the reagent in the dielectric gas to form agas-entrained reagent.

FIG. 5 is a block diagram of an embodiment of a reagent launcherconfigured to eject a stream, a pulse, or a spray of the reagentcarrying a voltage or charge.

FIG. 6 is a block diagram of an embodiment of a reagent launcherconfigured to output the reagent in the form of a gas phase reagent.

FIG. 7 is a flow diagram that outlines a method for operating a nitrogenoxide (NOx) control system, according to an embodiment.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. Other embodiments may be used and/or other changesmay be made without departing from the spirit or scope of thedisclosure.

FIG. 1 is a block diagram depicting a selective catalytic nitrogen oxide(NOx) reduction (SCR) system or a selective non-catalytic nitrogen oxide(NOx) reduction (SNCR) system 101, according to an embodiment. FIG. 2 isa block diagram depicting a charge-induced selective catalytic reduction(SCR) system 201 for reducing nitrogen oxides (NOx) to molecularnitrogen (N₂), according to an embodiment.

With reference to FIGS. 1 and 2, The SCR/SNCR systems 101, 201 include areagent charging apparatus 102 configured to apply electrical charges tomolecules, an aerosol, droplets, or particles of a reagent or a fluidcarrying the reagent to produce a charged reagent 106. A reagentlauncher 104 is operatively coupled to the reagent charging apparatus102. The reagent launcher 104 is configured to launch the chargedreagent 106 into a flue gas 110 produced by the combustion reaction 108.Typical reagents can include urea, cyanuric acid, aqueous ammonia,anhydrous ammonia, or coordinated ammonia reactants. Such reagents canbe referred to as ammoniacal reagents. The reagent can optionallyinclude a charge carrier mixed with the reactant. Optionally, theparticular reagent can be selected to accept a particular polarity ofcharge. For example, a cyano group can be relatively efficient ataccepting and holding a positive charge. In another example, an aminegroup can be relatively efficient at accepting and holding a negativecharge.

The primary difference between a SCR system 201 and a SNCR 101 system isthe respective presence or absence of a catalyst 204, which in turnaffects a temperature window within which chemical reduction of nitrogenoxide will occur. In an SNCR embodiment, a charged reagent is injectedabove the combustion reaction 108 in the flue gas 110 at a locationwhere the temperature is between about 1600° F. and 1800° F. (for anammonia reagent) or between about 1800° F. and 2100° F. (for a ureareagent). Below the temperature window, NOx reduction may substantiallynot occur. At temperatures above the temperature window, the chargedreagent can itself be converted to additional NOx.

In a SCR embodiment, a catalyst 204 lowers the NOx reductiontemperature. The catalyst bed 204 is typically held in a reductionchamber 202. Catalysts can include ceramic carrier with an oxide of abase metal such as vanadium, molybdenum, or tungsten; or a preciousmetal. As depicted schematically in FIG. 2, a charge-induced SCR system201 including the charged reagent launcher 104 is typically positionedfarther away from the combustion reaction 108 such that the temperatureof the flue gas 110 is further reduced compared to a charged reagentlauncher 104 used in a charged-induced SNCR system 101. Other thanpositioning, the charge-induced SCR 201 and SNCR 101 systems can operatesimilarly.

According to an embodiment, the charged-induced SNCR charged reagentlauncher 104 is positioned between the combustion reaction and asuperheater (not shown). According to another embodiment, thecharged-induced SNCR charged reagent launcher 104 is positioneddownstream from the superheater and upstream from a convective boilerstage (not shown). According to an embodiment, a charged-induced SCRcharged reagent launcher 104 is positioned downstream from a superheater(not shown) and upstream from a convective boiler stage (not shown).According to another embodiment, the charged-induced SNCR chargedreagent launcher 104 is positioned downstream from a convective boilerstage (not shown) and either upstream or downstream from an economizer(not shown) 203. Positioning of a charge-induced selective nitrogenreduction system, whether SCR or SNCR, can be adjusted according tooperating temperatures of the burner system 203, 103.

A counter charge, counter voltage, and/or ground electrode is used toattract the charged reagent. Referring to FIG. 1, in the SNCR embodiment101, a counter charge is shown as being provided by charging thecombustion reaction 108. If surfaces between the combustion reaction 108and the reagent launcher 104 are insulated or galvanically isolated,combustion reaction charging may similarly be used in SCR embodiment.Referring to FIG. 2, in the SCR embodiment 201, a counter voltage isshown as being provided by a counter electrode 206. The counterelectrode 206 can similarly be used in a SNCR embodiment. In a SCRembodiment (not shown) the catalyst bed 204 can be used as a counterelectrode. For example, a porous electrode structure (not shown) such asa screen can be embedded in the catalyst bed 204 or placed on a surfaceof the catalyst bed 204. In applications where the catalyst isconductive (as in a precious metal catalyst), the catalyst surfaceitself can operate as a counter electrode. Some catalysts operate byproviding a free electron to an ammoniacal group. In such cases,applying a positive charge to the reagent and a negative voltage to thecatalyst bed can aid in the electron-providing mechanism associated withthe catalyst surface.

Referring again to FIGS. 1 and 2, the reagent launcher 104 and thereagent charging apparatus 102 can together form a portion of a furnace,process heater or a boiler system 103. The reagent launcher 104 and thereagent charging apparatus 102 cooperate to cause a reduction in anamount of nitrogen oxide (NOx) species output by the furnace, processheater or the boiler system 103.

The furnace, process heater or a boiler system 103, in addition to theSCR/SNCR system 101, includes a burner 112 configured to support thecombustion reaction 108. A fuel and oxidant (e.g., air containingoxygen) is provided to the burner 112.

In an embodiment, the reagent charging apparatus 102 forms a portion ofthe reagent launcher 104. In another embodiment, the reagent launcher104 forms a portion of the reagent charging apparatus 102.

The SCR/SNCR system 101 includes a power supply 114 operatively coupledto the reagent charging apparatus 102. The power supply 114 isconfigured to apply electrical power as a high voltage to the reagentcharging apparatus 102. High voltage is defined as a (positive ornegative) voltage of 1000 volts or more.

The SCR/SNCR system 101 can include a reagent controller 116 operativelycoupled to the reagent launcher 104. Optionally, the reagent controllercan be one or more user-adjustable controls. In another embodiment, thereagent controller includes an electronic controller (e.g., amicrocontroller, PID controller, networked controller, etc.) configuredto select or control reagent control parameters.

Various reagent control parameters can be selected or controlled. Forexample, the reagent controller 116 can be configured to control aperiodicity of reagent launching and/or a flow rate of reagent launched.The reagent controller 116 can be operatively coupled to the powersupply 114. The reagent controller 116 can be configured to control thepower and/or voltage supplied by the power supply 114 to the reagentcharging apparatus 102, a counter electrode, and/or the combustionreaction.

The SCR/SNCR system 101 can include one or more sensors 118 operativelycoupled to the reagent controller 116 and/or to the furnace, processheater or boiler system 103. For example, the sensor 118 can measure aparameter that is related to operation of the SCR/SNCR system 101.Examples of such sensors 118 can include a nitric oxide (NO) sensor, anitrogen dioxide (NO₂) sensor, an ammonia (NH₃) sensor, an oxygen (O₂)sensor, a fuel flow rate sensor, a combustion reaction temperaturesensor, a flue gas temperature sensor, a combustion reaction radiationsensor, a voltage sensor, an electric field sensor, and/or a currentsensor. In some embodiments, multiple sensor types or sensor positionsare used to provide feedback to the reagent controller 116.

For example, a NOx sensor 118 can provide data to the reagent controllerindicative of higher-than-desired NOx concentration in the flue gas. Thereagent controller 116 can responsively increase the reagent chargedensity (e.g., by increasing the power supply voltage), increase thereagent flow rate, and/or decrease time between reagent injections. Inanother example, a temperature sensor 118 can sense temperature of aflue gas or combustion reaction at a reagent injection location. Thereagent controller 116 can determine if the temperature exceeds atemperature window for the NOx reduction reaction. If the temperature istoo high, the reagent controller can turn off the reagent launcher orreagent flow to the reagent launcher to avoid increasing NOx further.

Alternatively, the reagent controller 116 can change a reagent launchlocation or trajectory to a cooler location. Other control approachesfall within the scope of this application and will be apparent to oneskilled in the art.

In some examples, the reagent charging apparatus 102 and the reagentlauncher 104 are configured to cooperate to reduce the amount of NOxoutput compared to application of an uncharged reagent. In severalexamples, the reagent charging apparatus 102 and the reagent launcher104 can be configured to cooperate to reduce an amount of reagent usedto reach an amount of NOx reduction compared to application of anuncharged reagent.

According to an embodiment, the reagent charging apparatus 102 isconfigured to at least intermittently apply positive electrical chargeto the reagent. The positive electrical charges applied to the reagentmay be selected to form a higher equilibrium concentration of ammoniumions (NH₄ ⁺) in the charged reagent compared to an equilibriumconcentration of ammonium ions in the uncharged reagent. The higherconcentration of ammonium ions may be selected to cooperate with speciesin the combustion reaction to increase a rate of mass transport of anammonium or an ammonia species across at least a portion of thecombustion reaction 108 compared to a rate of mass transport of anuncharged ammonium or ammonia species. The higher concentration ofammonium ions may be selected to cooperate with NOx molecules toincrease a diffusion rate for pairing ammonium ions with NOx moleculescompared to an equilibrium concentration of ammonium ions in theuncharged reagent.

According to an embodiment, the reagent charging apparatus 102 isconfigured to at least intermittently apply negative electrical chargesto the reagent. The negative electrical charges applied by the reagentcharging apparatus 102 can be selected to induce radicalization ofammonia or urea to form aminyl radicals (.NH₂). Aminyl radicals may beconsidered NOx reduction reaction intermediates. Accordingly, thereagent charging apparatus 102 may be configured to cause an increase inconcentration of a SCR/SNCR reaction intermediate compared to anuncharged reagent.

In some examples, the electrical charges applied by the reagent chargingapparatus 102 can be configured to increase reactivity of the reagentwith NOx molecules in the flue gas 110 compared to an uncharged reagent.In several examples, the electrical charges applied by the reagentcharging apparatus 102 can be selected to increase mixing of the reagentwith the flue gas 110 compared to an uncharged reagent. In multipleexamples, the increased mixing can reduce ammonia slip, reduce NOxoutput, or reduce both ammonia slip and NOx output compared toapplication of an uncharged reagent.

In many examples, the SCR/SNCR system 101 can include a combustionreaction charging apparatus 120 configured to apply a voltage or chargeto the combustion reaction 108. For example, the charging apparatus 120can include an electrode supported in contact with the combustionreaction 108. In some examples, the charging apparatus is at leastpartially coextensive with a fuel nozzle configured to support thecombustion reaction 108.

The combustion reaction charging apparatus 120 may be configured toapply to the combustion reaction 108 a voltage or a majority chargehaving an instantaneous sign opposite of an instantaneous polarity ofelectrical charges applied by the reagent charging apparatus 102. Insome examples, the reagent charging apparatus 102 can be configured toapply a substantially constant charge concentration and polarity to themolecules, aerosol, droplets, or particles of the reagent or the fluidcarrying the reagent. In several examples, the reagent chargingapparatus 102 may be configured to apply a time-varying chargeconcentration, a time-varying polarity, or a time-varying chargeconcentration and polarity to the molecules, aerosol, droplets, orparticles of the reagent or the fluid carrying the reagent. When thereagent charging apparatus 102 applies a time varying polarity to thereagent, the combustion reaction charging apparatus 120 can be driven inopposition to the reagent charging apparatus such that the polarity ofthe combustion reaction and the polarity of the charged reagent areopposite of one another.

The reagent launcher 104 can include a reagent control valve (not shown)configured to control a flow rate of the reagent from a reagent sourceto a reagent mixer (not shown) or a reagent injector. A reagent mixermay include a Venturi or a length of tube (e.g., a constantcross-section tube) with an orifice configured to meter the nitrogenouscompounds into a carrier gas or to mix the reagent with charge carrierparticles.

FIG. 3 is a block diagram of an embodiment 301 of a reagent launcher104. In various examples, the apparatus 301 may be configured tovaporize and apply a charge to the reagent or a liquid carrying thereagent. In some examples, the reagent launcher 104 can include a body302 defining a vaporization or atomization chamber 304. The apparatus301 can include a pair of electrodes 306 a and 306 b configured to applya voltage-biased high voltage pulse to the reagent, thereagent-containing droplet, or the liquid carrying the reagent. Theapparatus 301 can include a reagent delivery passage 310 configured todeliver the reagent or the liquid carrying the reagent from a reagentsource 212 to the vaporization chamber 304. In some examples, the powersupply 114 can be configured to apply the voltage-biased high voltagepulse to the pair of electrodes 306 a and 306 b to cause the reagent orfluid carrying the reagent to vaporize and be ejected as a reagent vaporor aerosol 312 carrying the charged reagent 106.

The apparatus 301 can include a reagent controller 116 operativelycoupled to the power supply 114. The apparatus 301 can include a reagentcontrol valve 309 operatively coupled to the reagent source 212, thereagent delivery passage 310, and the reagent controller 116. In someexamples, the reagent controller 116 is configured to drive the reagentcontrol valve 309 to admit a quantity of reagent to the vaporizationchamber 304 via the reagent delivery passage 310. The reagent controller116 (if present) is configured to cause the power supply 114 to applythe voltage-biased high voltage pulse to the electrodes 306 a and 306 b.

The application of a high voltage pulse to a liquid causes the liquid tovaporize, in some examples without any substantial correspondingincrease in liquid temperature. By biasing the high voltage pulsepositive or negative, a corresponding charge may be placed on thevaporized liquid. For example, positive bias voltage can be caused byapplying a positive voltage on one electrode 306 a and holding the otherelectrode 306 b at ground. Alternatively, a positive bias voltage can becaused by applying a relatively large positive voltage on one electrode306 a and applying a negative voltage of lower magnitude on the otherelectrode 306 b. The positive bias voltage can cause the reagent vaporor aerosol 312 to carry a net positive charge. The positive charge maytend to be carried by nitrogenous compounds in the reagent.

In some examples, negative bias voltage can be caused by applying anegative voltage on one electrode 306 a and holding the other electrode306 b at ground. Alternatively, a negative bias voltage may be caused byapplying a relatively large negative voltage on one electrode 306 a andapplying a positive voltage of lower magnitude on the other electrode306 b. The negative bias voltage causes the reagent vapor or aerosol 312to carry a net negative charge. The negative charge may tend to becarried by the reagent.

The electrodes optionally can be configured to carry reversedcombinations of positive, negative, and ground pulses, as applicable.The reagent source 212 may hold a pressurized liquid such as a watersolution of dissolved ammonia. Alternatively, the reagent source 212 maybe configured to hold the reagent in the form of a solid dispersed in aliquid, for example, a urea slurry. Alternatively, the reagent source212 may be configured to hold anhydrous ammonia.

FIG. 4 is a block diagram of an embodiment 401 of a reagent launcher104. The apparatus 401 is configured to meter the reagent into adielectric gas. The apparatus 401 is configured to entrain the reagentin the dielectric gas to form a gas-entrained reagent 403. The apparatus401 is configured to eject a charge into the dielectric gas. Theapparatus 401 may be configured to deposit the charge from thedielectric gas onto the gas-entrained reagent 403.

The apparatus 401 may be configured to eject a stream, a pulse, or acloud of the gas-entrained reagent 403. In some examples, the reagentlauncher 104 can include a body 402 defining a gas flow passage 404 incommunication with a gas source and a region proximate to the flue gas110 produced by the combustion reaction 108. The apparatus 401 includesa reagent meter 410 configured to meter the reagent into a gas 408passing through the gas flow passage 404 to form the gas-entrainedreagent composition 403. The reagent charging apparatus can include atleast one corona electrode 414 configured to create a chargeconcentration in the gas 408 passing through the gas flow passage 404for depositing the charge on the metered reagent entrained in the gaspassing through the gas flow passage. The charges ejected by the coronaelectrode 414 may be deposited substantially completely on the reagent.Alternatively, charge carrier particles can be combined with thereagent, and the charges may be deposited on the charge carrierparticles.

The reagent launcher 104 includes a reagent control valve 412 configuredto control the supply of the reagent to the reagent meter 410. Thereagent controller 116 may be operatively coupled to and configured tocontrol the operation of the reagent control valve 412. A power supply114 is operatively coupled to the corona electrode 414.

FIG. 5 is a block diagram of another embodiment 501 of a reagentlauncher 104. The apparatus 501 is configured to eject a stream, apulse, or spray of a liquid 503 carrying a voltage or a charge and thereagent. In some examples, the apparatus 501 can be configured to ejectthe stream, the pulse, or the spray of liquid 503 carrying the chargedreagent 106. The reagent launcher 104 includes a nozzle 502 configuredto eject the stream, the pulse, or the spray including the reagent 106.The reagent charging apparatus 102 can be substantially coextensive withthe nozzle 502 or the reagent charging apparatus 102 can be operativelycoupled to the nozzle 502. A power supply 114 is operatively coupled tothe reagent charging apparatus 102 and configured to cause the reagentcharging apparatus 102 to apply the charge to the reagent.

In numerous examples of the apparatus 501, the power supply 114 can beoperatively coupled to a combustion reaction charging apparatus 120and/or to an attraction electrode (see, e.g., FIG. 2, 206). In variousexamples, the apparatus 501 includes a reagent control valve 504operatively coupled to the nozzle 502. The reagent control valve 504 canbe configured to control the flow of the reagent. In some examples, theapparatus 501 includes a reagent controller 116 operatively coupled tothe reagent control valve 504. The reagent controller 116 can beconfigured to cause the reagent control valve 504 to control the flow ofthe reagent.

In many examples, the apparatus 501 includes a reagent supply subsystem506. The reagent supply subsystem 506 can include a reagent tank 508operatively coupled to the nozzle 502. The reagent tank 508 can beconfigured to hold a liquid vehicle for carrying the reagent or a liquidreagent 510. In some examples, one or more electrical isolators 512 canbe operatively coupled to the reagent tank 508. The electrical isolators512 can be configured to maintain the reagent tank and the liquidvehicle for carrying the reagent or a liquid reagent 510 in electricalisolation from voltages or ground other than voltages or ground conveyedfrom a voltage source 114. The apparatus 501 can further include adielectric gap 514 formed between a reagent source 516 and the liquidvehicle for carrying the reagent or the liquid reagent 510. In someexamples, the apparatus 501 can further include at least a portion ofthe reagent source 516.

In addition to or in alternative to galvanic isolation of the liquidreagent tank 508, the liquid can be selected or treated to have lowelectrical conductivity. Galvanic isolation of such a liquid can includea relatively long non-conductive pipe having a length selected to limitor eliminate conduction through the liquid.

FIG. 6 is a block diagram of another embodiment 601 of a reagentlauncher 104 configured to output a gaseous reagent or a gas carryingthe reagent. The reagent launcher 104 includes a gas nozzle 604configured to output the gaseous reagent into the flue gas 110. Thereagent charging apparatus 102 (shown in FIG. 1) may further include anionizer 606 configured to cause charge ejection into the gaseousreagent. A gaseous reagent supply 602 can be operatively coupled to thegas nozzle 604 and the ionizer 606. The apparatus 601 can includereagent supply valve 608 operatively coupled to the reagent supply 602and the gas nozzle 604.

A reagent controller 116 can be operatively coupled to the reagentsupply valve 608 and configured to cause the reagent supply valve 608 tocontrol a flow rate of, or a periodicity of providing, the gaseousreagent from the reagent supply 602 to the gas nozzle 604. A powersupply 114 is operatively coupled to at least the ionizer 606 and can beconfigured to cooperate with the ionizer 606 to eject the charges intothe gaseous reagent.

The system 103, 203 can be configured to output heat from the combustionreaction. A subsystem (not shown) configured to receive heat from thecombustion reaction can include an industrial process, a gas turbine, aprocess material, a boiler, a furnace, a process heater, a prime mover,a power generation system, a commercial heating system, a commercialcooking system, or a commercial or residential hot water system, forexample.

FIG. 7 is a flow chart that shows a method 701 for operating a nitrogenoxide (NOx) control system, according to an embodiment. In variousexamples, the method 701 includes an operation 702 of applying firstelectrical charges to a SCR/SNCR reagent. The method 701 can include anoperation 704 of contacting the charged reagent into a combustionreaction or a combustion gas from a combustion reaction. The method 701can include an operation 706 wherein the electrical charge can beselected to enhance mixing of the SCNR reagent with NOx or to enhanceNOx reactivity of the reagent with NOx. The method 701 can include anoperation 708 to reduce the NOx to molecular nitrogen (N₂).

In some examples of the operation 702, applying first electrical chargesto the SCR/SNCR reagent can include applying first electrical charges tourea, ammonia, a solution including urea, or a solution includingammonia. In further examples of the method 701, operation 702 caninclude applying first electrical charges to the SCR/SNCR reagentcomposition by operating a reagent charging apparatus. In multipleexamples, operation 702 can include operating a power supply to applyelectricity to the reagent charging apparatus.

In various examples of the method 701, the operation 704 for injectingthe charged reagent into a combustion reaction or a combustion gas fromthe combustion reaction includes include operating a reagent launcher.In some examples, the method 701 can include (not shown) operating areagent controller to control a periodicity or a rate of reagentinjected into the combustion reaction or the combustion gas from thecombustion reaction.

In several examples, the method 701 includes include (not shown)operating at least one sensor. In many examples, the method 701 mayinclude operating the reagent controller responsive to a signal from theat least one sensor. In numerous examples, operating the at least onesensor includes operating a NO sensor. In various examples, operatingthe at least one sensor includes operating a NO₂ sensor. In someexamples, operating the at least one sensor includes operating anammonia sensor. In several examples, operating the at least one sensorincludes operating an oxygen sensor. In many examples, operating the atleast one sensor includes operating a combustion fluid flow rate sensor.In multiple examples, operating the at least one sensor includesoperating a combustion reaction temperature sensor. In numerousexamples, operating the at least one sensor includes operating acombustion reaction radiation sensor. In further examples, operating theat least one sensor includes operating a voltage sensor. In variousexamples, operating the at least one sensor includes operating anelectric field sensor. In some examples, operating the at least onesensor includes operating a current sensor.

Referring to FIG. 7 and to FIG. 3, operating the reagent launcher 104can include operating the apparatus 301 configured to vaporize and applya charge to the reagent or a liquid carrying the reagent. Referring toFIG. 7 and to FIG. 4, operating the reagent launcher 104 can includeoperating the apparatus 401 configured to meter the reagent into adielectric gas. In many examples, operating the reagent launcher 104 caninclude entraining the reagent in the dielectric gas. Operating thereagent launcher 104 can include ejecting a charge into the dielectricgas. In further examples, operating the reagent launcher 104 can includedepositing the charge from the dielectric gas onto the entrainedreagent. Referring to FIG. 7 and to FIG. 5, operating the reagentlauncher 104 can include operating an apparatus 501 configured eject astream, a pulse, or a spray of a liquid 503 carrying a voltage or acharge and including the reagent. Referring to FIG. 7 and to FIG. 6,operating the reagent launcher can include operating an apparatus 601configured to output a gaseous reagent or a gas carrying the reagent.

Referring to FIG. 7, the operation 702 for applying the first electricalcharges to the SCR/SNCR reagent and the operation 704 for injecting thecharged reagent into a combustion reaction or a combustion gas from acombustion reaction can include operating a reagent charging apparatusand a reagent launcher that are at least partially coextensive.

In multiple examples, applying the first electrical charges to theSCR/SNCR reagent includes applying a voltage include applyingelectricity to the reagent. In some examples, applying the firstelectrical charges to the SCR/SNCR reagent can include applying atime-varying charge to the reagent. In further examples, applying atime-varying charge to the SCR/SNCR reagent can include applying asequence of positive and negative charges to the reagent. In otherexamples, applying a time-varying charge to the SCR/SNCR reagent caninclude applying a pulsed charge of a single sign to the reagent. Insome examples, applying a charge to the SCR/SNCR reagent can includeapplying a charge of a single polarity to the reagent. In severalexamples, charging the SCR/SNCR reagent can include applying a positivevoltage to the reagent.

In some examples, charging the SCR/SNCR reagent includes applying anegative charge to the SCNR regent. Where the SCNR reagent compositionincludes ammonia or urea, the method 701 can include forming amide(NH₂-) ions from the ammonia or the urea. In further examples, themethod 701 can include decomposing the amide ions to aminyl radicals(.NH₂) after injecting the charged reagent. In several examples, theoperation 708 for reducing the NOx to molecular nitrogen includesreacting the aminyl radicals with nitric oxide to produce molecularnitrogen and water.

In several examples, operation 706 for enhancing reactivity of thereagent with NOx to operation 708 for reducing the NOx to molecularnitrogen can include causing reagent charging selected to increase arate of reaction.

In many examples, operation 706 for enhancing reactivity of the reagentwith NOx and operation 708 for reducing the NOx to molecular nitrogencan include causing reagent charging selected to decrease an averagedistance between the charged reagent molecules and NOx molecules.

In many examples, operation 706 for enhancing reactivity of the reagentwith NOx to operation 708 for reducing the NOx to molecular nitrogen caninclude causing the reagent to adopt an activated form selected toincrease attraction between the activated form of the reagent and NO.

In embodiments, the method 701 includes operation 712 of supporting thecombustion reaction. The method 701 can include operation 710 forproviding a fuel to support the combustion reaction. The operation ofproviding a fuel may include providing a hydrocarbon gas, a hydrocarbonliquid, or powdered coal, for example.

In some examples, the method 701 includes an operation 714 of applyingsecond electrical charges or a second voltage to the combustionreaction. The second electrical charges or voltage are opposite inpolarity from the first electrical charges. Applying a second voltage tothe combustion reaction can include operating the combustion reactioncharging apparatus such as a charge electrode. The charge electrode maybe at least partially coextensive with a burner configured to supportthe combustion reaction. The second voltage is opposite in sign from thefirst electrical charges. Alternatively, the operation 714 can includeapplying a second voltage and/or a ground potential to an attractionelectrode. The attraction electrode can be positioned to draw thecharged reagent across a flue or to a SCR catalyst bed.

In an embodiment, applying the first electrical charges to the reagentand applying the second voltage to the combustion reaction or theattraction electrode can include synchronously applying oppositepolarity time-varying electrical charges and/or voltages.

The method 701 can include decreasing NOx produced by the combustionreaction for a given heat output or decreasing an amount of the SCR/SNCRreagent usage for a given amount of NOx reduction compared to injectingnon-charged SCR/SNCR reagent, for a given heat output.

The method 701 can include applying heat from the combustion reaction toan industrial process, a gas turbine, a process material, a boiler, afurnace, power generation system, a prime mover, a commercial heatingsystem, or to a commercial or residential hot water system, for example.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments are contemplated. The various aspects andembodiments disclosed herein are for purposes of illustration and arenot intended to be limiting, with the true scope and spirit beingindicated by the following claims.

1.-103. (canceled)
 104. A selective nitrogen oxide (NOx) reductionsystem for a combustion reaction device, the system comprising: areagent charging apparatus configured to apply electrical charges to aselective nitrogen oxide reduction reagent, the reagent furthercomprising a SCR/SNCR reagent; and a reagent launcher configured tolaunch the charged reagent into a flue gas produced by the combustionreaction; the reagent launcher further comprising: a body defining achamber, a launch orifice configured to eject reagent, and a reagentdelivery passage configured to deliver the reagent or fluid carrying thereagent from a reagent source to the chamber; and at least oneelectrode, distinct from the body defining the chamber, disposed atleast partially within the chamber, within the launch orifice or withinthe delivery passage; wherein the at least one electrode is operativelycoupled to the reagent charging apparatus.
 105. The selective NOxreduction system of claim 104, wherein the reagent launcher and reagentcharging apparatus form a portion of a burner or boiler system andcooperate to cause a reduction in an amount of NOx output by the burneror boiler system.
 106. The selective NOx reduction system of claim 104,further comprising a burner configured to provide a fuel or a fuel andoxidizer to support the combustion reaction.
 107. The selective NOxreduction system of claim 104, wherein the reagent charging apparatusforms a portion of the reagent launcher.
 108. The selective NOxreduction system of claim 104, wherein the reagent launcher forms aportion of the reagent charging apparatus.
 109. The selective NOxreduction system of claim 104, further comprising: a power supplyoperatively coupled to the reagent charging apparatus and configured toapply electricity to the reagent charging apparatus.
 110. The selectiveNOx reduction system of claim 104, further comprising: a reagentcontroller operatively coupled to the reagent launcher and configured tocontrol a periodicity or a rate of reagent launched.
 111. The selectiveNOx reduction system of claim 110, further comprising: a power supplyoperatively coupled to the reagent charging apparatus and configured toapply electricity to the reagent charging apparatus; wherein the reagentcontroller is operatively coupled to the power supply and configured tocontrol the electricity applied by the power supply to the reagentcharging apparatus.
 112. The selective NOx reduction system of claim110, further comprising: at least one sensor operatively coupled to thereagent controller; wherein the reagent controller is configured tocontrol the periodicity or rate of reagent launched responsive to asensor signal received from the at least one sensor.
 113. The selectiveNOx reduction system of claim 104, wherein the reagent chargingapparatus is configured at least intermittently apply positiveelectrical charges to the reagent.
 114. The selective NOx reductionsystem of claim 113, wherein the positive electrical charges applied tothe reagent are selected form a higher concentration of ammonium ions([NH4+]) in the charged reagent than an equilibrium concentration ofammonium ions in the uncharged reagent.
 115. The selective NOx reductionsystem of claim 104, wherein the reagent charging apparatus isconfigured at least intermittently apply negative electrical charges tothe reagent.
 116. The selective NOx reduction system of claim 104,wherein the reagent includes ammonia or urea; and wherein the electricalcharges applied by the reagent charging apparatus are configured toinduce radicalization of ammonia or urea to form .NH₂.
 117. Theselective NOx reduction system of claim 104, wherein the electricalcharges applied by the reagent charging apparatus are configured toincrease reactivity of the reagent with NOx molecules in the flue gascompared to an uncharged reagent.
 118. The selective NOx reductionsystem of claim 104, wherein the electrical charges applied by thereagent charging apparatus are configured to increase mixing of thereagent with flue gas compared to an uncharged reagent.
 119. Theselective NOx reduction system of claim 104, further comprising: acombustion reaction charging apparatus configured to apply a voltage orcharge to the combustion reaction.
 120. The selective NOx reductionsystem of claim 119, wherein the combustion reaction charging apparatusis configured to apply, to the combustion reaction, a voltage ormajority charge having an instantaneous polarity opposite to aninstantaneous polarity of the electrical charges carried by the reagent.121. The selective NOx reduction system of claim 104, wherein thereagent charging apparatus is configured to apply a substantiallyconstant charge concentration and sign to the reagent.
 122. Theselective NOx reduction system of claim 104, wherein the reagentcharging apparatus is configured to apply a time-varying chargeconcentration, a time-varying charge polarity, or a time-varying chargeconcentration and polarity to the reagent.
 123. The selective NOxreduction system of claim 104, further comprising: an attractionelectrode configured to be held at a voltage opposite in polarity to thereagent charge, and to draw the reagent across a flue or toward acatalyst.
 124. The selective NOx reduction system of claim 104, furthercomprising: a catalyst bed.
 125. The selective NOx reduction system ofclaim 124, further comprising: a power supply operatively coupled to thecatalyst bed and configured to apply a voltage opposite in polarity tothe reagent charge to the catalyst bed.
 126. The selective NOx reductionsystem of claim 125, wherein a catalyst in the catalyst bed includes anelectrical conductor; and wherein the power supply is configured toapply the voltage to the catalyst.
 127. The selective NOx reductionsystem of claim 126, further comprising: wherein the voltage applied tothe catalyst by the power supply is negative polarity; and wherein thenegative polarity applied to the catalyst is selected to increase asupply of electrons to a reaction intermediate.
 128. The selective NOxreduction system of claim 104, wherein the reagent launcher furthercomprises: an apparatus configured to vaporize and apply a charge to thereagent or a liquid carrying the reagent.
 129. The selective NOxreduction system of claim 104, further comprising: a reagent controlleroperatively coupled to the power supply; and a reagent supply valveoperatively coupled to the reagent source, the reagent delivery passage,and the reagent controller; wherein the reagent controller is configuredto drive the reagent supply valve to admit a quantity of reagent to thevaporization chamber via the reagent delivery passage, and cause thepower supply to apply the voltage-biased high voltage pulse to theelectrodes.
 130. The selective NOx reduction system of claim 104,wherein the reagent launcher further comprises: an apparatus configuredto meter the reagent into a dielectric gas, entrain the reagent in thedielectric gas, eject a charge into the dielectric gas, and deposit thecharge from the dielectric gas onto the entrained reagent.
 131. Theselective NOx reduction system of claim 130, wherein the apparatus isconfigured to eject a stream, pulse, or cloud of gas-entrained reagent.132. The selective NOx reduction system of claim 104, wherein thereagent launcher 104 further comprises: a body defining gas flow passagein communication with a gas source and the flue gas produced by thecombustion reaction; and a reagent meter configured to meter the reagentinto gas passing through the gas flow passage; wherein the reagentcharger further comprises at least one charge ejecting electrodeconfigured to create a charge concentration in the gas passing throughthe gas flow passage for depositing the charge on the metered reagententrained in the gas passing through the gas flow passage.
 133. Theselective NOx reduction system of claim 132, wherein the reagentlauncher further comprises: a reagent control valve configured tocontrol the supply of reagent to the reagent meter; and a reagentcontroller operatively coupled to the reagent control valve andconfigured to control the operation of the reagent control valve. 134.The selective NOx reduction system of claim 104, wherein the reagentlauncher further comprises a nozzle configured to eject a stream, pulse,or spray including the reagent.
 135. The selective NOx reduction systemof claim 134, wherein the reagent charging apparatus is substantiallycoextensive with at least a portion of the nozzle.
 136. The selectiveNOx reduction system of claim 134, further comprising: a power supplyoperatively coupled to the reagent charging apparatus and configured tocause the reagent charging apparatus to apply the charge to the reagent;wherein the reagent charging apparatus is operatively coupled to thenozzle.
 137. The selective NOx reduction system of claim 136, whereinthe power supply is also operatively coupled to a combustion reactioncharging apparatus.
 138. The selective NOx reduction system of claim134, further comprising: a reagent control valve operatively coupled tothe nozzle and configured to control the flow of the reagent; and areagent controller operatively coupled to the reagent control valve andconfigured to cause the reagent control valve to control the flow of thereagent.
 139. The selective NOx reduction system of claim 134, furthercomprising: a reagent supply subsystem, the reagent supply subsystemfurther comprising: a reagent tank operatively coupled to the nozzle andconfigured to hold a liquid reagent; electrical isolators operativelycoupled to the reagent tank and configured to maintain the reagent tankand the liquid reagent in galvanic isolation from voltages or groundother than voltages or ground conveyed from a power supply; and adielectric gap formed between a reagent source and the reagent tank.140. The selective NOx reduction system of claim 104, wherein thereagent launcher further comprises: a gas nozzle configured to output agaseous reagent into the flue gas; and wherein the reagent chargingapparatus further comprises: an ionizer configured to cause chargeejection into the gaseous reagent.
 141. A method for operating anitrogen oxide (NOx) control system for combustion, comprising:delivering a reagent through a delivery passage to a chamber inside abody, the reagent further comprising a selective nitrogen reductionSCR/SNCR reagent; applying first electrical charges to the reagent byapplying the first electrical charges to at least one electrode, theelectrode being distinct from the body defining the chamber and beingdisposed at least partially within the chamber, within a launch orificeof the chamber or within the delivery passage; and injecting the chargedreagent, via the launch orifice of the chamber, into a flue gasresulting from a combustion reaction; wherein the first electricalcharge is selected to enhance mixing of the reagent with NOx or toenhance reactivity of the reagent with NOx to reduce the NOx tomolecular nitrogen (N₂).
 142. The method for operating the nitrogenoxide (NOx) control system of claim 141, wherein applying firstelectrical charges to a reagent includes applying first electricalcharges to urea, ammonia, a solution including urea, or a solutionincluding ammonia.
 143. The method for operating the nitrogen oxide(NOx) control system of claim 141, wherein applying the first electricalcharges to the reagent includes operating a reagent charging apparatus.144. The method for operating the nitrogen oxide (NOx) control system ofclaim 143, further comprising: operating a power supply to applyelectricity to the reagent charging apparatus.
 145. The method foroperating the nitrogen oxide (NOx) control system of claim 141, whereininjecting the charged reagent includes operating a reagent launcher, thereagent launcher further comprising the body, the electrode, thedelivery passage, and the launch orifice.
 146. The method for operatingthe nitrogen oxide (NOx) control system of claim 145, furthercomprising: operating the reagent controller to control a periodicity ora rate of reagent injected into the flue gas.
 147. The method foroperating the nitrogen oxide (NOx) control system of claim 146, furthercomprising: operating at least one sensor; wherein operating the reagentcontroller includes operating the reagent controller responsive to asignal from the at least one sensor.
 148. The method for operating thenitrogen oxide (NOx) control system of claim 145, wherein the chamber isa reagent vaporization chamber and the step of applying first electricalcharges includes vaporizing the reagent or a liquid carrying thereagent.
 149. The method for operating the nitrogen oxide (NOx) controlsystem of claim 145, wherein operating the reagent launcher includesoperating an apparatus configured to meter the reagent into a dielectricgas, entrain the reagent in the dielectric gas, eject a charge into thedielectric gas, and deposit the charge from the dielectric gas onto theentrained reagent.
 150. The method for operating the nitrogen oxide(NOx) control system of claim 145, wherein operating the reagentlauncher includes operating an apparatus configured to eject a stream,pulse, or spray of liquid carrying a voltage or charge and including thereagent.
 151. The method for operating the nitrogen oxide (NOx) controlsystem of claim 145, wherein operating the reagent launcher includesoperating an apparatus configured to output a gaseous reagent or a gascarrying the reagent.
 152. The method for operating the nitrogen oxide(NOx) control system of claim 145, further comprising: applying avoltage to an attraction electrode opposite in polarity to the firstelectrical charges.
 153. The method for operating the nitrogen oxide(NOx) control system of claim 141, wherein applying the first electricalcharges to the SCR/SNCR reagent includes applying a time-varying chargeto the reagent.
 154. The method for operating the nitrogen oxide (NOx)control system of claim 153, wherein applying a charge to the SCR/SNCRreagent includes applying a positive voltage to the regent.
 155. Themethod for operating the nitrogen oxide (NOx) control system of claim154, further comprising: forming ammonium ions (NH4+) from the reagent.156. The method for operating the nitrogen oxide (NOx) control system ofclaim 155, further comprising: after injecting the charged reagent,decomposing the ammonium ions to an .NH₂ radical; wherein reducing theNOx to N₂ includes reacting the .NH₂ radical with nitrogen monoxide (NO)to produce N₂ and H₂O.
 157. The method for operating the nitrogen oxide(NOx) control system of claim 153, wherein applying a charge to theSCR/SNCR reagent includes applying a negative charge to the regent. 158.The method for operating the nitrogen oxide (NOx) control system ofclaim 157, further comprising: forming NH₂-ions from the reagent. 159.The method for operating the nitrogen oxide (NOx) control system ofclaim 158, further comprising: after injecting the charged reagent,decomposing the NH₂-ions to an .NH₂ radical; wherein reducing the NOx toN₂ includes reacting the .NH₂ radical with nitrogen monoxide (NO) toproduce N₂ and H₂O.
 160. The method for operating the nitrogen oxide(NOx) control system of claim 141, further comprising: supporting thecombustion reaction.
 161. The method for operating the nitrogen oxide(NOx) control system of claim 141, further comprising: applying secondelectrical charges to the combustion reaction.
 162. The method foroperating the nitrogen oxide (NOx) control system of claim 161, whereinthe second electrical charges are opposite in sign from the firstelectrical charges.
 163. The method for operating the nitrogen oxide(NOx) control system of claim 161, wherein the second voltage isopposite in sign from the first electrical charges.
 164. The method foroperating the nitrogen oxide (NOx) control system of claim 161, whereinapplying the first electrical charges to the reagent and applying thesecond voltage to the combustion reaction include synchronously applyingtime-varying electrical charges and voltage, respectively.
 165. Themethod for operating the nitrogen oxide (NOx) control system of claim141, further comprising: applying heat from the combustion reaction toan industrial process, a gas turbine, a process material, a boiler, afurnace, a power generation system, a commercial heating system, acommercial cooking system, or a commercial or residential hot watersystem.
 166. The selective NOx reduction system of claim 104: whereinthe at least one electrode further comprises a pair of electrodesconfigured to apply a voltage-biased high voltage pulse to the reagentor the fluid carrying the reagent, within the chamber; and wherein thepower supply is configured to apply a voltage-biased high voltage pulseacross the pair of electrodes to cause the reagent or fluid carrying thereagent to vaporize and be ejected as a reagent vapor or aerosolcarrying the charged reagent.
 167. The selective NOx reduction system ofclaim 104, wherein the chamber is a reagent vaporization chamber. 168.The selective NOx reduction system of claim 104, wherein the launchorifice further comprises a venturi.
 169. The selective NOx reductionsystem of claim 168, wherein the delivery passage is disposed within theventuri launch orifice.
 170. The selective NOx reduction system of claim168, wherein the at least one electrode further comprises a coronaelectrode disposed within the venturi launch orifice.
 171. The methodfor operating the nitrogen oxide (NOx) control system of claim 141,wherein the at least one electrode further comprises a pair ofelectrodes, and wherein the step of applying first electrical chargesfurther comprises applying a voltage-biased high voltage pulse to thereagent or a fluid carrying the reagent across the pair of electrodes tocause the reagent or the fluid carrying the reagent to vaporize and beejected as a reagent vapor or aerosol carrying the charged reagent. 172.The method for operating the nitrogen oxide (NOx) control system ofclaim 141, wherein the chamber is a reagent vaporization chamber andfurther including a step of vaporizing the reagent.
 173. The method foroperating the nitrogen oxide (NOx) control system of claim 141, whereinthe launch orifice further comprises a venturi.
 174. The method foroperating the nitrogen oxide (NOx) control system of claim 173, whereinthe delivery passage is disposed within the venturi of the launchorifice.
 175. The method for operating the nitrogen oxide (NOx) controlsystem of claim 173, wherein the at least one electrode furthercomprises a corona electrode disposed within the venturi launch orifice.